U.S. patent number 4,117,846 [Application Number 05/816,952] was granted by the patent office on 1978-10-03 for skin conducting electrode and electrode assembly.
This patent grant is currently assigned to Consolidated Medical Equipment. Invention is credited to Frank R. Williams.
United States Patent |
4,117,846 |
Williams |
October 3, 1978 |
Skin conducting electrode and electrode assembly
Abstract
A disposable skin conducting electrode assembly and electrode
therefor for use on a patient wherein the electrode assembly
comprises an electrolyte pad, an electrode and an adhesive pad. In
one embodiment of the invention the electrode is a thin stainless
steel plate having a periphery shaped to provide a plurality of
recesses in the contour thereof and the adhesive pad is a solid
sheet having greater overall length and width dimensions than the
electrode. Thus the adhesive pad extends over the recesses in the
periphery of the electrode and provides greater adhesive area for
adhering the electrode assembly to the skin of the patient. An
external conductor is connectable to a conductive, single piece,
solid metal stud or post attached to the electrode extending
through an orifice in the adhesive pad. A pair of washers are
mounted on the stud on either side of the adhesive pad for
mechanically retaining the stud and electrode in position.
Inventors: |
Williams; Frank R. (Utica,
NY) |
Assignee: |
Consolidated Medical Equipment
(Utica, NY)
|
Family
ID: |
24747577 |
Appl.
No.: |
05/816,952 |
Filed: |
July 19, 1977 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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684317 |
May 7, 1976 |
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Current U.S.
Class: |
606/32 |
Current CPC
Class: |
A61N
1/0456 (20130101); A61N 1/0492 (20130101); A61N
1/0452 (20130101); A61N 1/0468 (20130101); A61N
1/048 (20130101) |
Current International
Class: |
A61N
1/04 (20060101); A61N 003/06 () |
Field of
Search: |
;128/303.13,404,410,411,416-418,2.6B,2.1R,DIG.4 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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122,258 |
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Feb 1972 |
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DK |
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2,239,596 |
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Feb 1974 |
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DE |
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2,208,653 |
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Apr 1973 |
|
DE |
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353,189 |
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Oct 1937 |
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IT |
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Primary Examiner: Cohen; Lee S.
Attorney, Agent or Firm: Larson, Taylor and Hinds
Parent Case Text
This is a continuation, of application Ser. No. 684,317 filed May
7, 1976, now abandoned.
Claims
I claim:
1. A skin conducting electrode assembly for use on a patient
comprising, in combination, an electrode, said electrode comprising
a thin conductive plate having a main body portion and a plurality
of projections around the periphery of the main body portion to
provide at least one recess in the contour thereof; means for
making an electrical connection to said electrode; an adhesive pad
in adhesive contact with one side of said electrode; a gel pad in
contact with the other side of said electrode, said gel pad
extending beyond the peripheral edges of the main body portion and
the projections of the electrode, said adhesive pad extending over
the at least one recess in the electrode and beyond the outer edges
of the gel pad around the entire periphery thereof, the at least
one recess between the projections being sufficiently large to
insure that when the electrode assembly is placed in contact with a
patient, the adhesive pad seals the assembly to the patient around
the periphery thereof and within the at least one recess in the
electrode to maintain the gel pad and electrode in firm contact
with the skin and the gel pad covers the entire face and edges of
the electrode to prevent direct contact of the electrode with the
skin of the patient.
2. A skin conducting electrode assembly according to the claim 1
wherein said plurality of projections provide substantial
conductive plate areas within the periphery of said
projections.
3. A skin conducting electrode assembly for use on a patient
comprising, in combination, an electrode, said electrode comprising
a thin conductive plate having a main body portion and a plurality
of projections around the periphery of the main body portion to
provide a plurality of recesses in the contour thereof, the
longitudinal distance across each of said recesses being at least
as large as the longitudinal distance across each of said
projections, means for making an electrical connection to said
electrode, an adhesive pad in adhesive contact with one side of
said electrode, a gel pad in contact with the other side of said
electrode, said gel pad extending beyond the peripheral edges of
the main body portion and projections of the electrode, said
adhesive pad extending over the recesses in the electrode and
beyond the outer edges of the gel pad around the entire periphery
thereof whereby, when the electrode assembly is placed in contact
with a patient, the adhesive pad seals the assembly to the patient
around the entire periphery thereof and within the recesses in the
electrode to maintain the gel pad and electrode in firm contact
with the skin and the gel pad covers the entire face and edges of
the electrode to prevent direct contact of the electrode with the
skin of the patient.
4. A skin conducting electrode assembly as claimed in claim 3
wherein said adhesive pad has an aperture therein, and said
electrical connection means comprising a conductive, one piece stud
fixedly mounted on said electrode and extending through said
aperture in said adhesive pad.
5. A skin conducting electrode assembly as claimed in claim 3
wherein said adhesive pad has an aperture therein, and said
electrical connection means comprising a conductive, one piece stud
fixedly mounted on said electrode, said stud terminating in a
helmet shaped cap having an outwardly extending flange at the
bottom, said stud extending through said aperture in said adhesive
pad, a first retaining washer held on said stud beneath said
outwardly extending flange and in contact with one side of said
adhesive pad and a second retaining washer on said stud in contact
with the other side of said adhesive pad.
Description
FIELD OF THE INVENTION
This invention relates to a skin conducting electrode and electrode
assembly. More specifically the present invention relates to a
disposable skin conducting electrode and electrode assembly
attachable to a patient for use as a return electrode during
electrosurgery or for use as an active electrode for applying an
electric current to a portion of a patient's body.
BACKGROUND OF THE INVENTION
Electrosurgery is the use of high frequency electrical current
(usually radio frequencies of 1 to 5 megahertz) for cutting tissues
and for also causing coagulation of hemostasis of tissues. It is
also used as an exclusive technique in transurethral resections
(TUR's) and laparoscopic tubal ligations. The basic mechanisms
responsible for either the cutting or coagulation of the tissues is
the production of heat either at the immediate site of the
electrical arc or in adjacent tissue. This heat is the result of
the unique properties of high frequency current with the current
density and duration of current flow being recognized as
determining the amount of heat generated in the tissue. Two basic
wave forms are used: an undamped sinusoidal wave form found most
useful for cutting tissue; and a series of highly damped sinusoidal
waves found most effective in coagulating tissue. High frequencies
are used in eletrosurgery because they will not stimulate the
patient's muscles and they are easily coupled into the tissues.
Although many standards exist for electrosurgical units, the
following have been proposed as appropriate approximations of the
characteristics of electrosurgical units. The units are normally
capable of delivering at least 150 watts of cutting power into 500
ohms of resistance. Coagulation power is at least 50 watts. The
load impedance is normally in the range between 100 and 1000 ohms,
the impedance varying depending upon the type of tissue (bone,
skin, fat or muscle,) location, (surface or underlying tissue), and
local blood circulation. The amount of current varies with the load
impedance, whether cutting or coagulation is being done, and the
type of surgery involved and can range from 2000 ma. for cutting
TUR down to 240 ma. for general coagulation use. Electrosurgery is
discussed in greater detail in volume 2 of "Health Devices", Issues
Nos. 8-9, 11, and 12 (June-October 1973), a monthly publication by
"Emergency Care Research Institute of Philadelphia,
Pennsylvania."
Electrosurgery, like all other uses of electricity, requires a
complete circuit for current to flow. The circuit begins at the
high frequency generator, goes through an active cable and an
active electrode to the patient (who constitutes the load) and
returns to the generator by way of a grounding pad electrode and a
cable attached therebetween. The ability of electrosurgical high
frequency current to affect tissue depends on the current density,
the greater the current density the greater the heating effect. If
the electrode is small, the heating will be concentrated near the
electrode's point of contact with a patient. Obviously this is
desired with the active electrode in order to cause the cutting or
coagulation of tissue. However, no tissue heating is desired near
the point where the current leaves a patient to return to the
electrosurgical unit. Thus the return electrode or grounding pad
electrode should provide a low impedance and a low current density
path for the return current. If the grounding pad electrode does
not provide a low impedance path for the return current, the
current will seek alternate means to return to the electrosurgical
unit and complete the circuit. Usually the alternate paths provide
high current density and tissue heating and burns on the patient
are the likely result. Thus, good patient contact with a return
electrode having very low current density is necessary to avoid the
alternate current pathways. Similarly, burns can occur at the
return electrode if there is inadequate patient contact with the
electrode to disperse the current. Thus, the use of an adequate
grounding pad electrode is necessary in order to assure safe,
burn-free electrosurgery.
Most hazards of electrosurgical units involve failure of the
electro-mechanical connection between the grounding pad electrode
and electrosurgical units or inadequate patient contact with the
grounding pad electrode. Grounding pad electrodes, therefore,
should conform to the patient, resist patient scratching, and
should have connectors that are rugged and able to withstand
routine use.
Because the body has an extremely low impedance to surface current,
the grounding pad electrode can be located almost anywhere on the
body. Nevertheless, in general the larger the electrode, the
flusher the electrode is to the skin, and the closer the electrode
is placed to the operating site, the lower will be the amount of
required electrosurgical power. Generally, the prior art electrodes
are applied around a curved area (e.g., the arm or leg) or comprise
a large metal plate that is placed beneath a large flat area of the
patient (e.g., the back or buttocks). However, in many operations
(such as a chest operation) the patient is placed on his side and
the arms are used for blood transfusions and sampling and for a
central vascular pressure monitor and the thighs may be used for
connections to a heart lung machine. Thus there is very little area
left on the patient on which to attach a conventional grounding pad
electrode.
There are numerous electrodes in the prior art and those presently
known to the applicant include the electrodes disclosed in the
following U.S. patents: Patrick, U.S. Pat. No. 3,848,600; Johnson
U.S. Pat. No. 3,830,229; Anderson U.S. Pat. No. 3,683,923; Estes
U.S. Pat. No. 3,601,126; Bolduc U.S. Pat. No. 3,543,760; Bolduc
U.S. Pat. No. 3,642,008; Bolduc U.S. Pat. No. 3,699,968; Bolduc
U.S. Pat. No. 3,720,209; Sessions U.S. Pat. No. 3,741,219;
Kawaguchi U.S. Pat. No. 3,685,645; Blackett U.S. Pat. No.
3,662,757; Smith U.S. Pat. No. 2,887,112; Consentino U.S. Pat. No.
3,580,240; Berman U.S. Pat. No. 3,085,577; Maurer U.S. Pat. No.
3,817,252; McDonald U.S. Pat. No. 3,386,445; Corasanti U.S. Pat.
No. 3,841,312 and Sarbacher U.S. Pat. No. 3,472,233. In addition,
the prior art is thoroughly discussed in the aforementioned "Health
Devices" magazine.
The aforementioned electrodes can be divided into disposable and
reusable electrodes. The reusable grounding pad electrodes usually
comprise a large metal plate made from lead, aluminum, or stainless
steel. These electrodes suffer from numerous disadvantages. These
plates are usually very large and rigid because of their thickness
and hence do not conform very well to the body contact area. In
addition, because the body contact area can be rounded, bony or
have irregular body surfaces, only a small contact area may be
presented to the large electrode, thereby resulting in burns. In
addition, the body contact area may be reduced by the layers of
sheets or surgical drapes being caught between the metal grounding
plate and the patient before and during the surgical procedure.
Finally, the plates require the body weight for contact and
therefore must be under the body. Because of the body contour,
there are only a few possible body locations at which these plate
electrodes can be used and the patient must usually be moved in
order to place the electrode which may be difficult because of the
patient's condition or weight. It may also be difficult to ensure
that the patient is in good contact with the electrode and that the
patient remains in good contact therewith despite deliberate
repositioning of the patient during the operation. In addition, the
large plate electrodes may not be usable with pediatric or
geriatric patients or patients having bony promiences or inadequate
weight.
Reusable solid metal grounding plate electrodes, in general, have
other disadvantages. The electrodes may become distorted, bent, and
cracked with frequent use and thus provide less effective contact
with the patient which may result in burns. Often the corners of
the electrode will curl if the electrode is dropped or the
electrode can be bent and distorted upon normal insertion and
removal from beneath the patient. Occasionally tissue necrosis has
occurred if the patient lies on a reusable electrode that has a
bent edge or corner, which causes great pressure over a small area.
In addition, the reusable electrode must be sanitized after each
use, are usually large and inconvenient to store, and are usually
expensive.
There are also available numerous types of disposable grounding pad
electrodes, generally classifiable into the "plate-type" and the
"adhesive-type". The plate-type disposable return electrodes are
usually made of cardboard with a conductive foil coating or
laminate on either one or both sides of the cardboard. The
additional expense of putting foil on both sides of the cardboard
has been justified to eliminate the possibility that the single
sided cardboard will be placed under the patient with the wrong
side (i.e., the cardboard side) against the patient. The
adhesive-type disposable grounding pad electrodes normally comprise
a conductive surface surrounded by an adhesive material. These
electrodes can be placed around an arm or a leg and depend on
adhesive, rather than the weight of the patient to hold them in
place.
Disadvantages of the plate-type disposable grounding pad electrodes
include splitting of the conductive surface after the electrode has
been bent, curling and delamination if the cardboard backed
electrodes become wet, are subjective to being torn, and the
requirement to use an electrosurgical gel in order to assure good
electrical contact with the skin. In addition to the foregoing, the
conventional adhesive- type grounding adhesive-type have a
generally smaller contact area and those which do not totally seal
on the patient have a tendency to become wrinkled if not properly
applied, have a tendency to lose their adhesive ability as a result
of contact with fluids on or near the patient or snagging of the
electrode, and must be applied around a curved area in order to
keep enough uniform inward pressure on the pad for even current
distribution. Furthermore, the use of both type electrodes often
requires considerable retraining of the personnel who apply the
electrodes to ensure proper application of the electrodes to the
patient.
Many of the adhesive-type disposable grounding pad electrodes are
also provided with a gel pad that is located in contact with the
metal electrode and is placed against the patient's skin so as to
assure a better electrical contact. One such electrode is disclosed
in the aforementioned Patrick et al U.S. Pat. No. 3,848,600. The
gel pad 32 disclosed therein is a very thick pad that is exposed to
the air along its outer edge, thus allowing gel evaporation during
long surgical procedures. The evaporation problem is exacerbated by
the heating of the pad caused by the operating current. Gel pad
drying results in increased contact impedance which in turn results
in a greater gel pad temperature which further dries out the gel
pad, and so forth.
Other difficulties experienced with prior art grounding pad
electrodes include chemical reactions with aluminum electrodes with
the resultant release of heat or caustic products and problems with
cable connection to the electrode. The latter problem occasionally
results in either the connecting cable coming loose or the coupling
post attached to the metal plate working loose or, in multipiece
posts, coming apart. The cable connection to the electrode assembly
must be designed so as to withstand the flexure and strains of
normal use. Numerous prior art electrode assemblies comprise a
multipiece connecting post that is held in contact with the
electrode plate by friction. This type of contact can result in a
greater electrical impedance and is subject to being worked
loose.
SUMMARY OF THE INVENTION
The present invention overcomes these and other disadvantages
disclosed in or apparent from the prior art. A skin conducting
electrode and electrode assembly in accordance with the present
invention provides a conveniently sized, inexpensive, disposable
device with a novel adhesive pattern that is flexible, provides
greater effective contact area and is usable on flat, cruved or
irregular body surfaces. Also this invention provides a
proportionately larger adhesive contact area, and is generally more
impervious to fluid damage after being applied to a patient. The
interface impedance of the present invention is approximately
equivalent to a continuous electrode having the same overall length
and width, but the present invention uses less electrode material
thereby providing greater material economics.
In one embodiment of the present invention, the adhesive pad
extends completely around the gel pad and utilizes a very thin gel
pad completely sealing the gel pad when the electrode assembly of
the present invention is applied to a patient. In further
embodiments of the invention, improved reliability of the
electrical connection is obtained with the use of a one-piece,
electrically conductive stud or post that is welded or brazed or
otherwise electrically and mechanically connected to the top
surface of the metal electrode plate. Finally, in a further
specific embodiment, the electrode assembly is given greater
mechanical strength and resistance to separation by anchoring the
metal stud to the adhesive pad with large non-conductive washers
sandwiching the adhesive pad.
When an electrode assembly according to the present invention is
appied to a patient, there is less possibility of injury to the
patient through restricted circulation as a result of the fact that
the present electrode assembly need not be placed around a limb,
and in fact need not even be placed on a limb. As a result of the
flexibility of the present electrode assembly and the greater
adhesion area actually extending into the electrode plate recesses,
the present assembly is less prone to wrinkling of the foil or the
foil curling up and cutting the patient. The present electrode
assembly easily conforms to the body surface and can be aplied over
bony areas, flat areas, and circular areas in any direction with
equal ease. Because the adhesive pad of the present electrode
assembly completely covers both the electrode and the electrolyte,
the electrolyte cannot dry out during prolonged use and the
electrode is protected against physical damage. Furthermore, it is
virtually impossible to place the present electrode assembly with
the wrong side against the patient.
In addition to being used as a grounding pad electrode for
electrosurgery, the present skin conducting electrode and electrode
assembly can be used in electrotherapy for wound healing, in
medical diathermy, in transcutaneous nerve stimulation and direct
nerve stimulation, and in muscle stimulation.
A skin conducting electrode in accordance with the present
invention comprises an elongated metal plate having a periphery
shaped to provide a plurality of recesses in the contour thereof. A
disposable skin conducting electrode assembly in accordance with
the present invention comprises the aforementioned electrode in
contact along one side thereof with an electrolyte composition and
an adhesive pad in adhesive contact along one side with the other
side of the electrode. The adhesive pad adheres the electrode
assembly to the skin of a patient and extends over the recesses in
the electrode and thereby provides additional adhesive area for
adhering to the skin of a patient.
Other objectives, features, and advantages of the present invention
are discussed in or are apparent from the description of the
preferred embodiment of the invention found hereinbelow.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an exploded perspective view of the components of the
skin conducting electrode assembly in accordance with the present
invention.
FIG. 2 is a bottom plan view of the electrode assembly showing the
hidden components thereof in phantom.
FIG. 3 is a top plan view of the present skin conducting electrode
assembly.
FIG. 4 is a side elevational view, somewhat enlarged, of the
connecting post or stud of the electrode assembly.
FIG. 5 is a cross-sectional elevational view taken along lines 5--5
of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT
It has been discovered that surface current readily disperses
laterally across a patient's skin and that there is extremely low
impedance to this lateral current dispersal. It has further been
discovered that gaps or recesses can be provided in a conducting
medium in electrical contact with the skin with almost negligible
effect on the skin-conductor interface impedance. In addition, a
negligible if any increase in electrical heating has been found.
For example, if a 3/4 inch square of material is removed from one
side of a two inch square of conductor material, only a maximum of
a few percent change of impedance has been observed. At the
aforementioned electrosurgery radio frequencies (1 to 5 MHz) large
recesses of up to 1 1/2 to 2 inches in larger plates apparently
produce little observed effect on interface impedance and electrode
heating.
With reference to the figures in which like numerals represent like
elements, an electrode assembly 10 is depicted which comprises an
electrolyte composition 12 in a gel pad 14, an electrode 16 in
contact along the bottom side thereof with the top side of gel pad
14, and a adhesive pad 18 in adhesive contact along the bottom side
the reof with the top side of electrode 16. A metallic, one-piece
post or stud 20 is fixedly mounted to the top surface of an
electrode 16 in electrical contact therewith and upper and lower
retaining washers 22 and 24 are located on either side of adhesive
pad 18 and are rigidly mounted and retained on stud 20.
As clearly shown in FIG. 1 and as shown in phantom in FIG. 2,
electrode 16 is comprised of an overall rectangular shape with
portions removed from either side. Viewed another way, electrode 16
comprises a main body portion 26 and a plurality of finger portions
28 integral with body portion 26 and extending outwardly in a
transverse direction therefrom. In the embodiment disclosed in
FIGS. 1 and 2, electrode 16 consists of 8 finger portions 28.
Adjacent finger portions 28 define therebetween a recess 30 in the
contour of electrode 16.
In one model made in accordance with the present invention, a
satisfactory electrode was made from 316 stainless steel foil
having a thickness of one thousandth of an inch. The model
electrode had an overall length of 6 3/4 inches and an overall
width of 2 1/4 inches. Finger portions 28 were constructed 2 inches
on center at a width of 3/4 of an inch thereby providing a recess
having a longitudinal length of 1 1/4 inches. Body portion 26 had a
transverse width of 1/4 inch thereby providing recesses 30 with a
transverse length of 1 inch. This particular electrode was found to
have an interface impedance that was approximately equivalent,
considering measuring difficulties and tolerances, as a rectangular
electrode having overall dimensions of 6 3/4 inches by 2 1/4
inches. It was also found that material economies were afforded by
having the "toothed-shape" of the electrode. This results by
maufacturing the electrode from large sheet materials and
interlacing the layouts of the electrodes and gel pads on the sheet
materials. For manufacturing ease, each of the corners of electrode
16 have a 1/4 inch radius. The elimination of sharp corners also
helps to prevent the electrical field concentration points and the
catching of finger portions 28 in other elements of electrode
assembly 10.
Gel pad 14 has a correspondingly similar shape as electrode 16 and
is comprised of a main body portion 32 and finger portions 34
integral therewith and extending in a transverse direction
outwardly therefrom. Adjacent finger portions 34 define recesses
36. In the model of electrode assembly 10, gel pad 14 was made from
one sixteenth inch thick 100 cpi "Scott Foam", a flexible cellular
material, and was impregnated with an conductive electrolyte
solution. As shown in FIG. 2, gel pad 14 is larger in each of the
dimensions than electrode 16. In the aforementioned model of the
invention, finger portions 34 of gel pad 14 were spaced 2 inches on
center, had a width of 1 inch and defined a recess 36 having a
longitudinal length of 1 inch. Body portion 32 has a transverse
length of 0.500 inches and gel pad 14 has an overall length and
width of 7 inches by 2 1/2 inches. Thus, recess 36 has an overall
transverse depth of approximately 1 inch.
Adhesive pad 18 has an upper, non-adhesive side 38 and a lower,
adhesive side 40 and is provided with an orifice 42 completely
therethrough. In the model of the invention, adhesive pad 18 was
made from 1/8 eighth inch thick 4 pound "White Foam" cross link
polyethylene material with an applied adhesive selected from a
group of adhesives that are medically compatible and are well known
to those of ordinary skill in the art. Adhesive pad 18 has a
generally rectangular configuration with rounded corners so as to
better ensure that the corners remain in adhesive contact when
applied to a patient. In the aforementioned model of the invention,
adhesive pad 18 had a length and width of 9 inches by 3 1/4
inches.
As shown in FIG. 2, adhesive pad is larger than both electrode 16
and gel pad 14 and extends over recesses 30 and 36 therein,
respectively. In addition, adhesive pad 18 has an overall length
and width larger than electrode 16 and gel pad 14 so as to extend
beyond the overall periphery thereof. Thus electrode assembly 10
provides pockets for adhesive pad 18 to appear through the larger
gel pad 14 which provides additional adhesive holding power of gel
pad 14 against the skin of a patient under all conditions of skin
contour for providing a better attachment of electrode assembly 10
to the patient during prolonged application and patient movement.
Furthermore, the added adhesive areas provided in electrode
assembly 10 maintan an intimate contact under contour and skin
tension change conditions which in the past have caused the prior
art electrodes to loosen the adhesive contact. Added advantages of
the component configuration in electrode assembly 10 with the thin
gel pad are that this configuration maintains an air tight seal
entirely around the periphery of the gel pad and prevents the gel
pad from drying out during use. The present electrode assembly 10
also can maintain a more positive attachment to a patient thereby
providing a lower contact impedance, a cooler electrode, and one
that can be placed closer to the operating site.
With reference to FIGS. 4 and 5, stud 20 consists of a solid,
one-piece stainless steel or other conductive material element
having a circular base 50, an upstanding pole portion 52 integral
with base 50, and a helmet-shaped cap 54 integral with pole portion
52. At the juncture between cap 54 and pole portion 52, cap 54 has
a flared out flange 56. By having stud 20 manufactured from a solid
metal, no cavities can exist therein for possible contamination and
the aforedescribed problems of multi-piece studs in the prior art
are avoided. As shown at 58 in FIG. 5 stud 20 is welded, brazed or
otherwise attached to the surface of electrode 16 thereby providing
positive, reliable, electrical and mechanical contact
therewith.
Improved mechanical strength of electrode assembly 10 is provided
by having the dimension of pole portion 52 slightly less than the
thickness of adhesive pad 18 thereby compressing and tightly
retaining adhesive pad 18 between flange 56 and base 50 of stud 20
and hence to electrode 16. Alternatively, improved strength of
electrode assembly 10 can be provided by retaining washers 22 and
24. As shown in FIGS. 1 and 5, lower retaining washer 24 is mounted
on stud 20 and abuts base 50 thereof. Stud 20 extends through
orifice 42 in adhesive pad 18 and upper retaining washer 22 is
mounted on stud 20 above adhesive pad 18. Flange 56 of stud 20
securely holds the sandwich formed by the two retaining washers 22
and 24 and adhesive pad 18 together and on stud 20. Since stud 20
is also securely fastened to electrode 16, the two washers also
have the effect of holding adhesive pad 18 to electrode 16. The
anchoring of adhesive pad 18 to stud 20 and electrode 16 in the
aforedescribed positive manners eliminates any danger of an
accidental pulling out of stud 20 through inadvertent tugs on a
grounding lead wire connected thereto during use.
In use, electrode assembly 10 is simply placed over the closest
available site to the operating location and is pressed onto the
skin 60 of the patient to adhere the adhesive of adhesive pad 18
thereto. It is usually standard practice to prepare the site where
the grounding pad is to be located by first shaving the area and
cleaning it with an antiseptic. A grounding wire (not shown) is
then connected at one end to stud 20 and at the other end to the
electrosurgery machine (also not shown).
Thus there has been described hereinabove a new and useful
disposable skin conducting electrode assembly and electrode
therefor for use on a patient undergoing electrosurgery or other
electrical treatment. Because of the flexibility, yet relatively
large effective area of the present electrode assembly 10, a skin
conducting electrode is provided which has a very low interface
impedance, less heat generation, can be securely attached to a
patient, provides a positive electrical connection between the
patient and the electrosurgery machine to complete the return path
for the current, and permits the use of a lower operating
power.
As mentioned above, a skin conducting electrode and electrode
assembly according to the present invention can also be used for
purposes other than a grounding pad electrode. When used as
grounding pad electrode, the embodiments of the present invention
are used as indifferent electrodes, but in the further
aforementioned applications of the present invention, the electrode
is used as an active electrode for applying an electrical current
to the skin. In these further applications, the size and
dimensions, as well as the external configuration, of the skin
conducting electrode can vary.
When used in medical diathermy, also called endothermy, short wave
diathermy, ultrasonic diathermy and medical thermopenetration, the
present electrode is used for applying high frequency currents to
the skin for the generation of heat in tissue as a result of the
resistance offered by the tissue to the passage of the current.
Although similar to electrosurgery, medical diathermy uses in
practice larger electrodes for skin contact since the desired
effect is only the generation of a heating or warming of muscles
and tissues for therapeutic purposes and not for causing tissue
destruction or blood coagulation. Medical diathermy is used
extensively in physical therapy to produce muscle relaxation.
The present skin conducting electrode and electrode assembly can
also be used for transcutaneous nerve stimulation. The "Gate
therapy" of pain introduced the use of electrical currents in the
treatment of chronic, irretractable or postsurgical pain. By
placing skin conducting electrodes over appropriate areas and
introducing currents having sufficient pulse widths and amplitude,
pain impulses can be blocked or overridden, thereby alleviating the
pain felt by the patient. In addition in many instances this type
of stimulation also reduces or eliminates the need for extensive
drug therapy and in other instances may be the only method for
treatment of a patient's pain. In practice, medical treatment of
pain associated with, for example, cancerous tumors, neurological
disorders, chronic headaches, orthopedic disorders and the after
effects of surgical trauma, can be accomplished by the transmission
of an electrical impulse from a generator to between a pair of skin
conducting electrodes positioned on the body in a configuration
that directs the electrical impulse toward the "Gate" or
susceptible point of a sensory nerve pathway. It is believed that
the applied electrical impulse overrides or interferes with the
transmission of the nerve pain impulse and hence eliminates or
reduces the patient's perceived pain. The present invention is
particularly applicable to transcutaneous nerve stimulation because
a large gel area is needed to lower skin impedance so that skin
burns can be prevented. The elongated and segmented configuration
of the present electrode assembly 10 permits the use of electrode
assembly 10 for treatment of immediate post-surgical pain since
electrode assembly 10 can be placed parallel to and along the
length of the surgical incision. In this manner, electrode assembly
10 can reduce the pain from surgical trauma and reduce the amount
of pharmaceutical pain-killing drugs and limit the associated side
effects of the drugs. Thus, the versatility provided by the present
electrode assembly 10 permits the electrode assembly to be applied
to almost any body area.
The present invention can also be used as an electrode for the
transmission of an electrical impulse for directly stimulating a
nerve or nerve pathway for restoring the physiological functions of
a damaged nerve system. When used for wound healing, an electrode
assembly according to the present invention can be used to apply an
electrical current for enhancing or promoting the healing of
traumatized, injured or displaced tissue. Long term application of
high frequency current, and in some cases low voltage DC current
can be accomplished with the present invention for aiding the
healing of bedsores or decubitis ulcers, surgical incisions, skin
ulcerations, and lacerations. Other wound healing applications can
be used to aid the setting and proper healing of broken bones and
fractured vertebrae, and even for treatment of curvature of the
spine.
A further additional use of a electrode assembly according to the
present invention is for muscle stimulation whereby electrical
currents are applied to stimulate muscle activity as part of
physical therapy that is needed because of nerve trauma or muscle
injury or damage.
The present invention is usable for the additional aforementioned
applications as a result of the ability of the present electrode
assembly to efficiently conduct electrical impulses to the skin of
a patient by allowing comformity of the electrode assembly to
irregular body surfaces without affecting electrical conductivity
and at the same time preventing tissue burn or adverse heating
reaction.
Although the invention has been described in detail with respect to
an exemplary embodiment thereof, it will be understood by those of
ordinary skill in the art that variations and modifications may be
effected within the scope and spirit of the invention.
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